Advice regarding OCP Java 6 exam

Hi folks,
looking for some friendly advice, hope I'm in the right place! I did the SCJP 1.4 exam back in early 2005, and I want to bring my certification up to date. I have been out of the certification loop for a while and I've only really started to look at it again recently. I see that the latest certification being offered is the Oracle Certified Professional 1.6 exam. This is the one I want to do, but I am unsure about which is the best way about doing it.

In the opinion of the readers, (and maybe somebody who's been in the same position), would the best approach be to do the Upgrade exam for the OCP 1.6 (CX-310-066), or should I just do the standard exam (CX-310-065)? I understand that the upgrade exam just contains questions about the new topics, and the pass mark is higher. I am unsure what these new topics are since 1.4 (or does the upgrade exam just contain differences between the 1.5 and 1.6 exam?). Is there a list of these topics, and if there are what is the best study guide to prepare for them? (Sierra & Bates 1.6?)

I guess I'm looking for the quickest way of achieving the OCP 1.6 certification, preferably without having to slog through the entire study guide again. Would be grateful for any advice/pointers.